Book Review – Why We Run by Bernd Heinrich, 1995
I just finished reading the book Why We Run and found it to be an interesting read about human and animal evolution relating to movement. The author, Bernd Heinrich, is a biologist with a unique background that would make an interesting story in and of itself. His parents, also biologists, raised him and his sister in the Maine woods in a somewhat primitive manner. For six formative years, the two kids lived in a boarding school while his parents lived in Angola doing field research. It was at school that Heinrich became interested in running. He realized that succeeding at cross country would give him the possibility of going to college on scholarship.
He went to the University of Maine and excelled in running and in his studies. During his final year of college he had the opportunity to join his parents on their last great expedition. His job during the fourteen months he was in Africa was to hunt birds for a museum collection. While hunting for specimens, he did a lot of running – barefoot. He fancied the notion that many African and Native American tribes had hunting traditions of chasing down animals until they tire. He wondered how that practice fit into our evolutionary changes.
Much of this book examines different animal species and how they have adapted to move and feed themselves. Heinrich is convinced that we are born to run, hence the topic of the book. He talks about how we evolved from lobe-finned ancestors that crawled onto land with four limbs and evolved to become adept bipedal savanna hunters. Some interesting questions addressed by Heinrich include, does multipedalism increase or decrease speed? Cheetahs are considered fast runners and they are quadripedal, and cockroaches (a six legged insect) are one of the smoothest and fastest moving insects. Yet we have just two legs. What advantages, if any do we have with just our two legs?
He discusses the body’s ability (be it a frog or dinosaur) to deliver a continuous supply of oxygen to muscles with the support of lungs, hemoglobin and myoglobin, and the role of fast and slow twitch muscle fibers. He compares how heat production is managed by different species during exertion. Humans have evolved to get rid of heat through sweating, but how do bumblebees and butterflies stay cool when exerting? He compares the ability of a variety of species to fuel muscles during an endurance event. Have you ever wondered how birds can travel 3500 miles without eating or drinking? What about bulky bears that hibernate for six months and eat nothing? How do camels go for days in blistering heat without drinking a drop of water? Why are animals for the most part not prone to obesity like we are? These and a number of other interesting questions are explored by Heinrich in this book.
My favorite parts of the book, of course, relate to Heinrich’s inferences to biochemistry and nutrition. He points out that in our evolutionary history, we were forced to be continually active in order to survive, and therefore never had the necessity to deal with the effects of prolonged idleness. One of the obvious byproducts of our idleness is obesity. This is because our bodies are evolutionally programmed to store excess calories as fat in preparation for lean times. When was the last time you had a lean time? Not only can this make us fat, but trying to get weight off once stored is very difficult. He advocates that we should try to lose our excess fat stores with a gradual caloric reduction to avoid the body’s metabolic response to plummet as if in a starvation mode. This is hard for us to accept as we want to lose weight fast and are disappointed when we don’t experience immediate results. He shares the idea that regional differences in body composition abound today due to this evolutionary safety net, like the Polynesian people of the South Pacific. These remote islands were colonized by a specific subgroup of survivors-people who had been adrift for months at sea. During these long distance movements that resulted in chance colonizations, those leaving on their journeys with the largest buffer of energy reserves would have lived longer and plausibly more likely reached land than those starting off lean. This ability to store fat was passed on as a survival trait.
Another interesting aspect that I had not thought of that Heimlich points out is the effect that contemporary idleness has on our bones. Running had become a constant in our past lives in the form of hunting and gathering. Now that we are much more sedentary, our bones have suffered. Data show that our bones become brittle and weak (osteoporosis) if they don’t receive normal everyday stress. We see an accelerated form of this effect with astronauts who live at zero gravity for just a short period of time. Heinrich points out that bears that are completely inert during hibernation suffer no such bone loss. They are not programmed for constant movement. We may need to consider movement as a supplement for optimum health, like we do vitamin and mineral supplements.
To carry out his theme of being born to run, Heinrich weaves his personal running experiences throughout the book. Upon his return to college, he was fit and anxious to letter in track and break the school record. His final race of his college career, however, was disappointing and he did not achieve his goal. He was crushed, but not defeated. Twenty years later, Heinrich decided to use his knowledge of animal physiology to attempt to win the U.S. National 100 kilometer championship. He was 41 years old and felt he was passing his peak. He calculated he would need to run this 100 km race in 6.5 hours to beat the record; an average pace of 6:17.
Heinrich reports his running efficiency improved dramatically. As he trained, he gradually increased his weekly mileage. Early on, he could barely make it home without bonking. As his fitness improved, he found that he ran out of fuel less often and at a later time during a run. He surmises that his body learned to burn a combination of carbs and fats and/or that he had trained his muscles and liver to store more glycogen. Both are most likely true, but it doesn’t solve the puzzle completely. As he became more fit and was often running 20 miles per day (120 miles per week), he reports that he was not eating much more than he used to, and his weight stayed fairly constant. At 100 kcals per mile, that is 2000 extra kcals he needed to take in per day. He claims he ran more mileage with the same number of calories. I see this with my clients who are ultra-runners all the time. You would think they could eat an ox with the miles they run, but they can’t and don’t. Perhaps, he was becoming more efficient with his stride, his gate and his respiration (resting heart rate went from 60 to 34 bpm), all of which can affect calorie expenditure. I would love to hear about anyone’s personal experiences with this as it continues to be a mystery to me. Please share your ideas.
Overall, I found this to be a very interesting book. As a runner and a nutritionist, I agree with his simple approach to run and eat what his body told him to eat (antelope seem to have figured this out). No Gu, Nuun or protein powders for him. I believe the overall take home message for us is that we are meant to be continually active and mobile (read run) and that when we do we are healthy, both mentally and physically. So get moving!